Smoke Em

ive been using Valvoline syn. 5w30, but now my oil pressure has dropped at idle,once warm, to very low like 2 - 3 psi. the car runs fine and the pressure is fine when driving. I have heard from some people that it is better to run regular motor oil in these cars because its heavier giving it more pressure.

my z has 76k miles and i replaced the oil sending unit twice in the past 2 days because the pressure dropped low at idle and it never did that before it would always hold at 20. the first time i replaced it because i had the intake off to replace the gaskets and rtv and it was easy to do so i did it

i still have to check the pressure with a mechanical gauge to be 100% positive

to get the pressure up can i use a different weight oil, if so what do you suggest

pillarpod

Valvoline Sny all the way

96blackz28

iTrader: (3)

I run 10-30 Mobile 1 Synthetic, car has 146k on it and still runs amazingly strong. I had a similar problem with my oil pressure and it had me concerned but i dumped about an extra half quart of oil over the add mark and it helped. Im geussing my oil pump is on its last leg. But once heated up pressure is anywhere from 10-25psi.

2-3 sounds like an issue, i would hook up a mechanical guage, or you can also try running a half bottle of sea foam in your oil for about 150miles to get rid of any sludge that could be blocking your oil pump.

^^ I did the sea foam deal and my oil pressure stays more stable s ince

96blackz28

iTrader: (3)

Oh yea forgot to mention, if you do the sea foam in your oil trick, change oil and filter after about 100-150miles!

Smoke Em

anyone try running a heavier oil to increase oil pressure

gregrob

iTrader: (8)

Go get some DELO 15-40 Diesel Engine Oil

EAO SHOT

Try a K&N oil filter. It will bring your oil pressure up.

86formula

iTrader: (3)

i run Amsoil 25-50, no problems at all

leadfoot4

iTrader: (1)

A heavier oil will bring up your pressure a bit, but if it suddenly dropped as you describe, it ISN'T the oil causing the loss. You have a problem somewhere, such as a plugged filter, plugged filter bypass, or a plugged intake screen on the pump's pick up.

Smoke Em

it didnt drop like i made it sound over 20 mins it will gradually fall at idle only,
the pressure is the best it has ever been driving at 1500 its about 40 psi so i cant complain about that

sorry for that confusion

96blackz28

iTrader: (3)

plugged intake screen is why i recommened sea foam, but the OP didnt seem to care

Smoke Em

why do you have to change the filter after 100 miles???

leadfoot4

iTrader: (1)

Because the SeaFoam dillutes the oil, as well as dislodging any junk that's in the engine, and makes it float around. You want that crap to drain out....


Secondly, my point was that you car had good oil pressure at idle at one time, didn't it? It didn't just happen because you put syn oil in it right? Simply changing oil won't cause huge fluctuations in oil pressure. 2-3 PSI at idle is a HUGE problem, if indeed that's the case, and not a gauge malfunction. Plain old water should give you more than 2-3 PSI, assuming the pumping system is working properly. Maybe the bypass spring in the pump has gummed up, or somehow malfunctioned....

Smoke Em

no it had good oil pressure with the synthetic oil in it, until i changed the oil sending unit
the oil pressure was fine

93Z2871805

iTrader: (5)

A good old trick to clean the motor is to add 1qt trans fluid with your next oil change. So if you use 4.5-5qts normally go 3.5-4qts oil then 1qt auto trans fluid. The reason is the trans fluid is high detergent and does not break down like motor oil. I had a friend try this with a NASTY 455 olds. He changed his oil once a week doing this and repeated for about a month. The oil that started as this thick tar on his valve covers looked so clean after he was done you could eat off them.

Smoke Em

i dont think that anything is clogging the intake on the oil pump or anything like that
so back to the topic what is the best oil for a lt1???
is synthetic bad or is regular motor oil better?

baalic

iTrader: (8)

A mobile 1 oil filter is the exact same internals and cheaper......


Synthetic is always better for your engine, it doesn't run "thinner" it runs the same. Hence why its rated at 5w30 10w30 etc...... There was another topic on this as well regarding which "synthetic" to use. Synthetic is always better then conventional because of the detergents and the fact its not going to burn off leaving nice carbon deposits etc. It doesn't break down as easy as conventional.

What I have been using, for some time in all of my vehicles is Mobile 1 Full Synthetic and recently I have switched to Royal Purple which imo works just a little better. On your LT-1 You may try going with a 10w30 unless you live in a place that is constantly below freezing. It adds a little more weight at cold engine temperatures and should bring oil pressure up a little, but I agree with whoever said that if its reading 2 or 3 lbs then its not the oil.....do you always change your oil filter when you change oil?? Mobile 1 oil filters are cheaper then the K&N and have almost the exact same internals. The difference is a "Nut" on the K&N filter. You said you didn't have a problem until you changed a sending unit or something, that right there should tell you what the problem actually is.

10w30, or 5w30 for winters if harsh... Mobile 1 Full Synthetic, or Royal Purple, Mobile 1 Oil Filter. That's my suggestion.

leadfoot4

iTrader: (1)

But didn't you say you have only 2-3 psi of oil pressure at idle??? Changing oil ISN'T going to change that!!

You have a problem!! It might be as simple as a gauge problem, but nonetheless, you have a problem of some kind......

Smoke Em

the car was idling fine after i changed the oil, the oil is not the problem
it idled at 20 for 2 months with the synthetic oil in the car,


im gonna get a mechanical gauge tomorrow and prove that there is oil pressure at idle

im just wondering if i can use a heavier weight oil without any problems

kierstyn

iTrader: (5)

Mobile 1 all the way!